Yes, I'm sure you're sick to death of threads like this but I think Tobi pretty much just confirmed it in the latest Naruto chapter.
Given everything else we know about Tobi.
- Sharingan only in one eye. Conveniently his other eye has always not been shown, the same eye which was given to Kakashi.
- Wasn't half his body all bolted up and his head, torso and legs were all shown to be bandaged up too.
- He uses Space/Time Ninjutsu and surprise surprise Kakashi's MS is also a Space/Time Ninjutsu. No other MS user has shown such an ability.
For me, it's as clear as day that Tobi is Obito. Everyone thinks that it would be too obvious but what you have to remember is that Kishimoto already knows how this manga is going to end and he's not going to change such a big point in the story just because everyone figured out who Tobi was fairly easily.
Any opinions? People have said he was Madara or Danzo but given current evidence I'd say that both are impossible.